Evaluation of farmers storage structures and their effects on the quality of sorghum grain in Wa, West District in the Upper West Region of Ghana

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Grain storage structures have a great influence on the quality of the stored produce. The level of insect-pest infestation, damages or losses and overall quality of the stored produce over a period of time depends on the kind of storage structure used. Therefore, the study was conducted in Wa West District from January to July, 2013 with the aim to identify the common storage structures used in the storage of grain sorghum and evaluate their effects on the quality of stored sorghum. A survey was first conducted through the administration of questionnaire, personal observation and discussion to seek farmers’ relevant knowledge with regards to the sorghum storage structures used by farmers, reasons for preferences and constraints of sorghum storage in the district. All communities in the district were put into five major clusters or zones and four communities were randomly selected from each cluster for the survey. Data gathered from the survey were analysed using Statistical Package for Social Scientist (SPSS) version 16 and presented in the form of pie charts, bar charts, histograms and tables. The experimental results were analysed using GENSTAT 9.2 Edition and means separated using Least Significance Difference (LSD) at 5% and the results presented in tables and graphs. It was revealed from the study that the major sorghum storage structures farmers used in the district were mud silos (35%), barns (15%), polypropylene bags (18.3%), jute sacks (12.5%), store rooms (houses) (8.4%), Purdue Improved Crop Storage (PICS) bags (5.83%), and baskets (2.5%) while 2.5% of the farmers stored in other structures such as earthen pots and metal containers (basins). Mud silos were the most preferred storage structures used by farmers with baskets and earthen pots been the least. Mud silos were the most preferred due to the numerous advantages associated with them. The use of storage structures by farmers were constraint by high insect infestation, structural failures, difficulties in acquiring structures, rodent destruction, inadequate capital to acquire storage structures and chemicals, transportation difficulties and high cost of the storage facilities. Further to the survey, field experiment was conducted to determine grain losses and evaluate the effects of the major sorghum storage structures used by farmers on grain quality. The grain of local sorghum variety (kazie) cultivated by majority of the farmers in the area was acquired after harvesting and stored in five common used grain storage structures (mud silo, barn, polypropylene bag, jute sack (bag) and PICS bag) with 100 kg each in a Complete Randomised Design (CRD) of three replications for each storage structure or treatment for 210 days (7 months). Samples were taken every 30 days (one month) interval for the determination of relevant parameters such as moisture content, insect count (live and dead), purity test, germination test, 1000-seed weight, weight loss, temperature and relative humidity of the storage structures. PICS bag kept the grains at mean lower moisture content, lowest insect population (28 live ones), lowest mean relative humidity (45.9%), lowest average grain loss (3.2%) caused by the major insect pest - lesser grain borer (Rhyzopertha dominica) that infested grains in the storage structures. Percentage mean grain loss caused by insects was highest in jute sack (8.2%) while that of PICS bag (3.2%) was the lowest, suggesting that PICS bag were better in maintaining the quantity and quality of the grain under storage. There was no significant difference (p>0.05) in germination and weight loss among the storage structures. Lowest germination losses (5.5%) occurred in the mud silo with greatest losses in jute sack (14.2%). Unthreshed grain stored in mud silo showed an overall better germination (90%) than the rest of the storage structures. However, there was no significant difference in the germination percentages among grain stored in the various storage structures. Correlation coefficient (r) analysis showed that weight loss strongly positively correlation with live insects, dead insects, moisture content and relative humidity (r>0.05). Therefore, insects, moisture content and relative humidity were the major influential factors responsible for loss. The purity test at the end of storage revealed that jute sack had high percentage of inert matter (4.7%) with mud silo recording the lowest (2.4%).
A thesis submitted to the School of Rresearch and Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the award of Master of Philosophy degree in Postharvest Technology.